Rapid identification of behaviorally relevant objects is important for survival. In humans, the neural computations for visually discriminating complex objects involve inferior temporal cortex (IT). However, less detailed but faster form processing may also occur in a phylogenetically older subcortical visual system that terminates in the amygdala. We used binocular rivalry to present stimuli without conscious awareness, thereby eliminating the IT object representation and isolating subcortical visual input to the amygdala. Functional magnetic resonance imaging revealed significant brain activation in the left amygdala but not in object-selective IT in response to unperceived fearful faces compared to unperceived nonface objects. These findings indicate that, for certain behaviorally relevant stimuli, a high-level cortical representation in IT is not required for object discrimination in the amygdala.

Rapid identification of behaviorally relevant objects is important for survival. In humans, the neural computations for visually discriminating complex objects involve inferior temporal cortex (IT). However, less detailed but faster form processing may also occur in a phylogenetically older subcortical visual system that terminates in the amygdala. We used binocular rivalryto present stimuli without conscious awareness, thereby eliminating the IT object representation and isolating subcortical visual input to the amygdala. Functional magnetic resonance imaging revealed significant brain activation in the left amygdala but not in object-selective IT in response to unperceived fearful faces compared to unperceived nonface objects. These findings indicate that, for certain behaviorally relevant stimuli, a high-level cortical representation in IT is not required for object discrimination in the amygdala.

Excerpt from the researchers article

Results

In binocular rivalry, perceptual dominance is promoted by “stimulus strength,” as defined by characteristics such as high luminance and high contrast, transient motion, and complexity (Blake, 2001)…………………………

. This presentation scheme (Figure 1) maintained the perceptual suppression of the target image during the entire trial. In addition to presentations of suppressed chairs and suppressed fearful faces, we also included a third condition in which a moving house was presented to both eyes, in order to compare responses to this nonrivalry condition. These three conditions were indistinguishable to the participant, appearing as a moving house in every case.

. These three conditions were indistinguishable to the participant, appearing as a moving house in every case.

Rapid identification of behaviorally relevant objects is important for survival. In humans, the neural computations for visually discriminating complex objects involve inferior temporal cortex (IT). However, less detailed but faster form processing may also occur in a phylogenetically older subcortical visual system that terminates in the amygdala. We used binocular rivalry to present stimuli without conscious awareness, thereby eliminating the IT object representation and isolating subcortical visual input to the amygdala. Functional magnetic resonance imaging revealed significant brain activation in the left amygdala but not in object-selective IT in response to unperceived fearful faces compared to unperceived nonface objects. These findings indicate that, for certain behaviorally relevant stimuli, a high-level cortical representation in IT is not required for object discrimination in the amygdala.

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Results

In binocular rivalry, perceptual dominance is promoted by “stimulus strength,” as defined by characteristics such as high luminance and high contrast, transient motion, and complexity (Blake, 2001)…………………………

. This presentation scheme (Figure 1) maintained the perceptual suppression of the target image during the entire trial. In addition to presentations of suppressed chairs and suppressed fearful faces, we also included a third condition in which a moving house was presented to both eyes, in order to compare responses to this nonrivalry condition. These three conditions were indistinguishable to the participant, appearing as a moving house in every case.

. These three conditions were indistinguishable to the participant, appearing as a moving house in every case.......